About possible Babelfish J interest

Official Court Jester
Joined 2003
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you didn't

ZM is notorious for not making and hating BOMs

when making something , I'm always making mine own from schm and pcb directly

:rofl:

will post tonight/tomorrow two sets of schematics , along with wiring tips - just base pcb (pair of mosfets) and base pcb + daughter boards (up to 3 pairs of mosfets)
 
Official Court Jester
Joined 2003
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Base pcb iteration - up to so-so normal rails

so , just base pcb and pair of IRFP150 mosfets for output

schematic and screenshot of pcb attached ; sch cleaned from some Eagle necessary clutter

observe pics in posts #35 and #36

populate pcbs as usual , all resistors are garden variety MF small jobbies except big 0R27 ones - use either Panasonic MOX 3W or square whitish 5W wirewounds

for these - mount just two pcs in group of 6 pcs

for all 0R27s - use 6-8mm risers between resistor body and pcb during soldering , to ensure good ventilation and prevent pcb heating in exploatation

prior to soldering on pcb - be sure that all multiturn pots are in mid position - confirm that with ohmmeter

wire as any of FW amps , input RCA isolated from chassis , use tiniest wire for input signal - twisted pair is preferable to coax

again , FW PSU style used - with these parts values you're good up to +/-30Vdc - take care to not exceed 50W dissipation per mosfet , under condition that you don't have more than 50C on heatsink , even in summer time

main gnd bus from PSU to pcb , then from pcb to speaker negative output
post

powering up - connect everything , ground inputs , no load on output

power up ;

if green LEDs are lit , that means two things - you mount them all as needed..... and there is proper biasing voltage for LTP cascodes ;)

- check voltage across R11 - set 10V there with TP2 and we'll have 10mA through input LTP

-check voltage across R29 ; 540mV will inform as of 2A Iq ; use less if you want ; correct with TP3 if needed

- check voltage at output node - chase 0V ( up to 30mV is OK , + or - , irrelevant) , correct with TP1

last two steps are somewhat inter-dependable ; repeat them iteratively until you get desired Iq and zero offset

of course , last two steps are also dependable of open lid/closed lid situation, but you already know that final setting must be made in temperature equilibrium state , where closed lid is normal thing

so , be prepared to use few voltmeters , extending wire-clips and to open lid-set-close lid not overly slow

:cheers:

edit : yes - JMP parts are jumpers - either normal solid core bridges or fancy 0R resistors

don't forget to mount them , too :clown:

later - some more sketches - how to properly wire extended iteration
 

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Official Court Jester
Joined 2003
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addendum (editing time closed) :

C8 and C9 need to be , say , 35V jobbies , all other 'lytics are good up from 16V

C1 and C2 values - whatever you have in drawer and you can squeeze on pcb , up to 47uF

transistors , bjt - I sent you all small critters ; Q4 - any decent PNP in T0126 case , take care of pinout - look at BD139 datasheet for info - face front , pins down , ECB left to right
 
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Official Court Jester
Joined 2003
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470uF 'lytics on rails - whatever you have in drawer from 220uF upwards , 25V as minimum and 35V if you're having higher rails

same for two last 470uF ones ; C4 is 220 to 1000uF , decent quality 16V minimum , C7 is 220 to 1000uF 16V minimum and that one need to be best quality you have (Silmic , yup) bypassed with 1uF MKC I sent you ; it's for Aleph CCS modulation and sole critical cap position in entire amp

ZD5V1 , across Q9 - as per A W Newby instruction , intended for softer and more normal behavior of Aleph CCS near clipping ; use either 5V1 or 5V6 plain small zener diode , 250 to 500mW variety


C5 - usual suspect is silver mica ........ or take decent stacked smd cap , not smallest one but biggest ( easier to eyes and fingers ) solder some cuts of resistor legs on it and place through hole in position
modern smd ceramic caps are almost good as preputium expensive silver mica from yore , and you can buy them in every tobbacco store nowadays ..... if there is tobacco store near you :rofl:

birds and roosters around are awake now at my place ...... I think that I'm going to take a nap

:clown:
 
Official Court Jester
Joined 2003
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Similar to buzzforb's Funny F6?

...

well , yes and not ;
without digging deep again in Buzz's thread (and I believe I wrote enough there ) I believe we had more than one iteration having SUSY implemented ... but not all ; one of goals was to have several things achieved , one is SUSY and another was proper coupling between two xformers

after some time I'm always ending either slightly confused or just not remembering anymore , what's done and what's not :rofl:
price for my usual multitasking (read - bumblebee flying from flower to flower)

in short ,any iteration of X amp is by principle - SUSY

so , GR's thread is good place for start but , if I go that route , I would implement greater amount of details leading to more foolproof* design

*meaning - easier for set and having proper servo ; so that needs time , not just taking older schm and blah!just producing a product
 
Yes, I meant J271 to replace 2SJ74BL. LOL, without the morning coffee, the brain was lesser than half way working, only 3 out of 7 letters of the jfet came to the mind :)

J271 is also obsolete. It is just a just touch easier to find than the 2SJ74BL. I came cross a US site still has 300 in stock; hence, I asked :)
 
populate pcbs as usual , all resistors are garden variety MF small jobbies except big 0R27 ones - use either Panasonic MOX 3W or square whitish 5W wirewounds

for these - mount just two pcs in group of 6 pcs

Hi ZM,
Can you clarify "mount just two pcs in group of 6 pcs"

R29, R30, R31, R32 are the 0R27 with R31 parallel with R32. Do you mean substitute single 5W 0R135 instead of R31 & R32 or use either R31 or R32 but not both? :confused: